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RE: TODO++: daml-ont TallThing

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Fri, 3 Nov 2000 21:45:08 +0000 (GMT)
To: "Hart, Lewis" <lhart@grci.com>
Cc: "McBride, Brian" <bwm@hplb.hpl.hp.com>, www-rdf-logic@w3.org
Message-ID: <14851.10357.194979.932389@localhost.localdomain>
On November 3, Hart, Lewis writes:
> >From: Ian Horrocks [mailto:horrocks@cs.man.ac.uk]
> >Sent: Friday, November 03, 2000 4:46 AM
> >To: McBride, Brian
> >Cc: www-rdf-logic@w3.org
> >Subject: RE: TODO++: daml-ont TallThing
> >
> >
> >On November 1, McBride, Brian writes:
> >> > > There are a couple of minor nits in the example ontology:
> >> > > 
> >> > > 1) Father is desribed as having range Man, but presumably
> >> > >    inherits domain Animal from Parent.  Mother is similar.
> >> 
> >> A mother of a fox is not human.  I'd expect the domain and range
> >> to match i.e. domain of mother is person if range is woman, or
> >> range of mother is female animal if domain is animal.
> >> 
> >> A real nit - sorry.
> >> 
> >> Brian
> >
> >This is another example of a point I made in an earlier discussion on
> >rdf-interest, namely that domain and range restrictions are very
> >strong assertions, and that a value restriction on the domain class is
> >usually more appropriate. 
> >
> >For example, when the domain and range of a property P are restricted
> >to classes D and R respectively, the intended meaning often is (or
> >should be) that IF (i,j) is an instance of P AND i is an instance of D
> >THEN j must be an instance of R. ...
> 
> So, do this mean that once you have said, in ontology O1:
> 
> <Class ID="D">
>   <restrictedBy>
>     <Restriction>
>       <onProperty resource="#P"/>
> 
>       <toClass resource="#R"/>
> 
>     </Restriction>
>   </restrictedBy>
> </Class>
> 
> no one else could say, in ontology O2:
> 
> <Class ID="D">
>   <restrictedBy>
>     <Restriction>
>       <onProperty resource="#P"/>
> 
>       <toClass resource="#R2"/>
> 
>     </Restriction>
>   </restrictedBy>
> </Class>
> 
> For example, let D := Person, P := authorOf, R := Book, and R2 := Ontology 

No problem. This is equivalent to saying that the the range
restriction is the intersection of Book and Ontology.

> It seems to be preferred to use restrictions at the most general level they
> apply. In my example restricting authorOf to "AuthorableThings" which has
> Book and Ontology as subclasses.

You can do this too. You could also set the restriction class to the
union of book and ontology if you believe that they are a covering of
"AuthorableThings".

> I am not sure how this could be determined
> a priori in the web environment. But, the more general class could be
> inferred as a requirement for working simultaneously with statements
> expressed in O1 and O2.

Ian
Received on Friday, 3 November 2000 16:50:02 UTC

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